This invention relates to amorphous alloy-based metallic finishes which are resistant to wear and corrosion, processes for obtaining these finishes, and suitable applications for using these finishes to provide anti-wear surfaces, and particularly in hydraulic equipment.
In the following description, these metallic finishes will be primarily described by reference to their applications onto metal substrates. It is, however, within the scope of the present invention to apply these metallic finishes to non-metal substrates such as wood, paper, synthetic substrates and the like.
Solutions are being sought in numerous fields to overcome the problems associated with wear due to abrasive erosion, scoring and friction in aggressive surroundings, and cavitation. These particular problems are especially severe in hydraulic equipment such as turbines.
The materials presently being used are generally hard, but they are fragile and accordingly their users are seeking materials which provide the following improved combination of properties: (1) increased hardness to resist the harmful effects of erosion, friction and scoring; (2) high ductility to resist shocks and minor deformations; and (3) homogeneous structures to assure uniform high corrosion resistance.
The materials which are presently available, such as steels having high mechanical properties, stellite, ceramics, and the like, do not have all these properties. In particular, those materials having high corrosion resistance have insufficient mechanical properties.
One of the solutions so far for obtaining materials having a satisfactory compromise of these contradictory properties has been metal alloys having amorphous structures that have been obtained by rapid cooling techniques.
The amorphous alloys that have so far been used are essentially in the form of thin strips obtained by casting methods or very thin deposits obtained by electrochemical methods.
The thermal projection methods and, for example, the arc-blown plasma method, have not yet enabled the obtaining of completely amorphous alloys at the level of X-ray diffraction in the form of thick (i.e., &gt;0.5 mm) powder deposits on surfaces as large as several square meters.
Among the various known amorphous alloys are the iron-based metal/metalloid alloys (Fe--B or Fe--Cr--P--B alloys) which have provided the best mechanical properties. However, none of these alloys have satisfied the contradictory requirements of increased mechanical resistance, corrosion resistance and high ductility.